The present invention relates to electroactive compounds, namely, compounds capable of undergoing a change in light absorption and refraction when subjected to an outside influence, the use of such electroactive compounds in compositions to make electroactive compositions, the use of such electroactive compositions to make electrooptical devices, such as modulators of light in integrated optic or fiber optic systems, as well as methods of making the foregoing compounds, compositions and devices.
The basis of the many aspects of the various embodiments of the present invention is the novel electroactive compound within the novel classes of electroactive compounds of the present invention. The electroactivity of the compounds, and therefore, the compositions and devices incorporating them, is based upon the delocalized pi-electron system which exhibit nonlinear optical response. In addition, the electroactive compounds of the present invention have an unusual ability to undergo a permanent change in refraction upon exposure to certain predetermined wavelengths of optical radiation which permits a type of photolithographic process to create optical waveguides in compositions containing the electroactive compounds of the present invention.
Electrooptical modulators, switches and optical parametric devices based upon the nonlinear optical properties of materials are known in the art. Generally, these devices have utilized inorganic crystals, e.g., LiNbO.sub.3. In addition, due to the electronic states associated with the effect, the organic crystalline materials not only have large intrinsic second order nonlinear optical susceptibilities, but potentially possess very fast switching time.
It is known that organic and polymeric materials with large delocalized pi-electron systems can exhibit nonlinear optical response, which in many cases is a much larger response than by inorganic substrates.
In addition, the properties of organic and polymeric materials can be varied to optimize other desirable properties, such as mechanical and thermooxidative stability and high laser damage threshold, with preservation of the electronic interactions responsible for nonlinear optical effects.
Thin films of organic or polymeric materials with large second order nonlinearities in combination with silicon-based electronic circuitry have potential as systems for laser modulation and deflection, information control in optical circuitry, and the like.
Other novel processes occurring through third order nonlinearity such as degenerate four-wave mixing, whereby real-time processing of optical fields occurs, have potential utility in such diverse fields as optical communications and integrated optical circuit fabrication.
Of particular importance for conjugated organic systems is the fact that the origin of the nonlinear effects is the polarization of the pi-electron cloud as opposed to displacement or rearrangement of nuclear coordinates found in inorganic materials.
Nonlinear optical properties of organic and polymeric materials was the subject of a symposium sponsored by the ACS division of Polymer Chemistry at the 184th meeting of the American Chemical Society, September 1982. Papers presented at the meeting are published in D. C. Williams, Ed., ACS Symposium Series 233, American Chemical Society, D. C. (1983). The above recited publications are incorporated herein by reference.
The fundamental concepts of nonlinear optics and their relationship to chemical structures can be expressed in terms of dipolar proximation with respect to the polarization induced in an atom or molecule by an external field. The concepts and theory are now well known to those skilled in the art as represented by the papers published in the ACS Symposium Series 233 cited and incorporated herein by reference above.